Stochastic Physics Namelist

General options

Option Description
NTRUNC Optional, Spectral resolution (e.g. T126) of random patterns, default is for model to determine proper truncation
LAT_S Optional, number of latitude points for the gaussian grid (must be even), default is for model to determine gaussian grid
LON_S Optional, number of longitude points for the gaussian grid (recommend 2xLAT_S, default is for model to determine gaussian grid
FHSTOCH Optional, forecast hour to write out random pattern in order to restart the pattern for a different forecast (used in DA), file is stoch_out.F<HHH>
STOCHINI Optional, set to true if wanting to read in a previous random pattern (input file needs to be named stoch_ini).

SPPT options

Option Description
DO_SPPT logical to tell parent atmospheric model to use SPPT
SPPT Amplitudes of random patterns (0.8,0.4,0.2,0.08,0.04) *
SPPT_TAU Decorrelation timescales in seconds (21600,1.728E5,6.912E5,7.776E6,3.1536E7) *
SPPT_LSCALE Decorrelation spatial scales in meters (250.E3,1000.E3,2000.E3,2000.E3,2000.E3) *
SPPT_LOGIT Should be true to limit the SPPT perturbations between 0 and 2. Otherwise model will crash.
ISEED_SPPT Seeds for setting the random number sequence (ignored if stochini is true)
SPPT_SIGTOP1 lower sigma level to taper perturbations to zero (default is 0.1)
SPPT_SIGTOP2 upper sigma level to taper perturbations to zero (0.025)
SPPT_SFCLIMIT .T.=tapers the SPPT perturbations to zero at model’s lowest level (helps reduce model crashes)
SPPTINT Optional, interval in seconds to update random pattern. Perturbations still get applied every time-step
USE_ZMTNBLCK .T.=do not apply perturbations below the dividing streamline that is diagnosed by the gravity wave drag, mountain blocking scheme

* SPPT uses 5 different patterns of varying time/length scales that are added together before being passed to physics

SHUM options

Option Description
DO_SHUM logical to tell parent atmospheric model to use SHUM
SHUM Amplitudes of random patterns (0.004)
SHUM_TAU Decorrelation timescales in seconds (21600)
SHUM_LSCALE ecorrelation spatial scales in meters (250000)
SHUM_SIGEFOLD e-folding lengthscale (in units of sigma) of specific humidity perturbations, default is 0.2)
SHUMINT Optional, interval in seconds to update random pattern. Perturbations still get applied every time-step
ISEED_SHUM Seeds for setting the random number sequence (ignored if stochini is true).

SKEB options

Option Description
DO_SKEB logical to tell parent atmospheric model to use SKEB
SKEB Amplitudes of random patterns (0.5)
SKEB_TAU Decorrelation timescales in seconds (21600)
SKEB_LSCALE Decorrelation spatial scales in meters (250)
ISEED_SKEB Seeds for setting the random number sequence (ignored if stochini is true).
SKEBNORM 0-random pattern is stream function, 1-pattern is K.E. norm, 2-pattern is vorticity (default is 0)
SKEB_VARSPECT_OPT 0-gaussian (default), 1-power law (not tested)
SKEB_NPASS number of passes of the del2 smoothing for the dissipation estimate (default is 11, minimum is 3)
SKEB_VDOF the number of degrees of freedom in the vertical for the SKEB random pattern (default is 5)
SKEB_SIGTOP1 lower sigma level to taper perturbations to zero (default is 0.1)
SKEB_SIGTOP2 upper sigma level to taper perturbations to zero (0.025)
SKEBINT Optional, interval in seconds to update random pattern. Perturbations still get applied every time-step